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Characterization of algal and microbial community growth in a wastewater treating batch photo-bioreactor inoculated with lake water
Mälardalen University, School of Business, Society and Engineering, Future Energy Center. (ACWA)ORCID iD: 0000-0002-4435-4367
Mälardalen University, School of Business, Society and Engineering, Future Energy Center.ORCID iD: 0000-0001-5480-0167
Indian Institute of Technology, Bombay, India..ORCID iD: 0000-0001-8857-4903
University of Tartu, Estonia.ORCID iD: 0000-0003-1818-6678
Show others and affiliations
2015 (English)In: Algal Research, ISSN 2211-9264, Vol. 11, no Sept, 421-427 p.Article in journal (Refereed) Published
Abstract [en]

Microalgae grown in photo-bioreactors can be a valuable source of biomass, especially when combined with wastewater treatment. While most published research has studied pure cultures, the consortia of algae and bacteria from wastewater have more complex community dynamics which affect both the biomass production and pollutant removal. In this paper we investigate the dynamics of algal and bacterial growth in wastewater treating batch photo-bioreactors. The photo-bioreactors were inoculated with water from a nearby lake. Lake water was obtained in August, November and December in order to add native algal species and study the effects of the season. The photo-bioreactors inoculated with lake water obtained in August and November produced more biomass and grew faster than those that only contained the algae from wastewater. The results indicated a rapid decline in bacterial abundance before algae began to multiply in reactors supplemented with lake water in November and December. The reactors were also successful in removing nitrogen and phosphorous from wastewater.

Place, publisher, year, edition, pages
Elsevier, 2015. Vol. 11, no Sept, 421-427 p.
Keyword [en]
Algal cultivation; Biomass production; Community analysis; Photo-bioreactors; Wastewater treatment
National Category
Water Treatment
Research subject
Energy- and Environmental Engineering
Identifiers
URN: urn:nbn:se:mdh:diva-27699DOI: 10.1016/j.algal.2015.02.005ISI: 000363046900051Scopus ID: 2-s2.0-84943663075OAI: oai:DiVA.org:mdh-27699DiVA: diva2:795354
Funder
Knowledge Foundation, 2011006VINNOVA, 2012-01243
Note

Additional funding from SVU (12-123), Purac and Mälarenergi, and by grant IUT2-16 of the Ministry of Education and Research of the Republic of Estonia (J. Truu, M. Truu, T. Ligi).

Available from: 2015-03-16 Created: 2015-03-16 Last updated: 2017-01-03Bibliographically approved
In thesis
1. Communities of microalgae and bacteria in photobioreactors treating municipal wastewater
Open this publication in new window or tab >>Communities of microalgae and bacteria in photobioreactors treating municipal wastewater
2015 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Everyone who uses water produces wastewater. This inevitability creates several problems that increase with the growth of the population and industry. What to do with the wastewater, how to purify it and how to design the infrastructure are all important questions that each municipality has to deal with, taking into account ever growing demands to reduce environmental impact. In these conditions scientists and engineers have turned to biological processes to help treat the water. Currently the most commonly used wastewater treatment method known as the activated sludge process involves bacteria that help break down the pollutants. While it has been used successfully for around 100 years now, it has many limitations when faced with modern demands. As an alternative, microalgae reactors, commonly known as photobioreactors, have been suggested.

Microalgae are microscopic water organisms that can use photosynthesis to form sugars from CO2 and water. To do this they require energy from light, hence the photo part of the photobioreactor. In addition to taking up CO2 from their environment, they take up nutrients such as nitrogen and phosphorous compounds. This is a reason why microalgae have great potential for use in wastewater treatment. When grown in wastewater together with the microorganisms already present, they are able to reduce the amount of pollutants by taking them up into their cells, effectively purifying the water.

Since wastewater has its own microbial community, the biological processes taking place in a wastewater treating photobioreactor are more complex compared to growing a single species of algae in a sterile medium. With the work presented in this licentiate, we characterized the algae and bacterial communities present in photobioreactors treating wastewater in addition to finding the most optimal ways to grow algae originating from a local lake in a wastewater medium. We looked at the species found, most important metabolic pathways, growth dynamics for both algae and bacteria and water purification dynamics.

Overall, we were successful in inoculating municipal wastewater from Västerås wastewater treatment plant with algae from Lake Mälaren. The dominant algae growing in our systems belonged to the genera Scenedesmus, Desmodesmus and Chlorella. We also saw that the bacterial community was involved in synthesis of vitamins essential for algae growth. The information presented in this thesis is another step towards a better design of control and monitoring systems in full-scale photobioreactor plants.

Place, publisher, year, edition, pages
Västerås: Mälardalens högskola, 2015
Series
Mälardalen University Press Licentiate Theses, ISSN 1651-9256 ; 193
National Category
Water Treatment
Research subject
Energy- and Environmental Engineering
Identifiers
urn:nbn:se:mdh:diva-27696 (URN)978-91-7485-192-2 (ISBN)
Presentation
2015-04-17, Lambda, Mälardalens högskola, Västerås, 10:00 (English)
Opponent
Supervisors
Funder
Knowledge Foundation, 2011006VINNOVA, 2012-01243
Note

Additional funding was from SVU (12-123), Puracand Mälarenergi, and by grant IUT2-16 of the Ministry of Educationand Research of the Republic of Estonia (J. Truu, M. Truu, T. Ligi).

Available from: 2015-03-17 Created: 2015-03-16 Last updated: 2015-06-11Bibliographically approved
2. Microbiological analysis of municipal wastewater treating photobioreactors
Open this publication in new window or tab >>Microbiological analysis of municipal wastewater treating photobioreactors
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Microalgae reactors, commonly known as photobioreactors, have become increasingly popular as an alternative for wastewater treatment. These systems reduce pollutants and remove nutrients such as nitrogen and phosphorous compounds from wastewater utilizing microalgae and bacteria. The biomass produced in the reactors can potentially be used to produce biofuels and decrease some of the energy demands of the process.

Wastewater treating photobioreactors are a relatively new technology and many aspects of their microbiology need further study. This thesis presents a broad overview of the algal and bacterial communities present in these systems by looking at the most important species, metabolic pathways and growth dynamics of both algae and bacteria.

The experiments presented in this thesis were conducted using municipal wastewater from the Västerås wastewater treatment plant. The wastewater was inoculated with algae from Lake Mälaren and compared to non-inoculated reactors. Overall, the inoculated reactors demonstrated better algal growth than those that were not inoculated. The tested systems also removed much of the ammonium and phosphorous present in the wastewater.

The dominant algae in the tested systems belonged to the genera Scenedesmus, Desmodesmus and Chlorella. In addition to algae, the systems contained a large number of bacteria, mostly from the phyla Proteobacteria and Bacteroidetes.

The algal photobioreactors contained a lower abundance of genes related to nitrogen metabolism, virulence and antibiotic resistance compared to the initial wastewater, showing that a shift in the bacterial community had occurred. The bacteria found in the systems were shown to be involved in synthesis of vitamins essential for algae growth such as vitamin B12, suggesting cooperation between the bacteria and algae.

Abstract [sv]

I takt med att världens befolkning ökar, så produceras dagligen allt mer avfall. Detta kan orsaka stora problem för miljön. När det byggs nya system för vattenrening behöver vi även ta hänsyn till kravet att minska energiåtgången. Dagens vattenreningssystem har vissa tillkortakommanden när det gäller reningsnivåer och energianvändning. Ett alternativ till dagens system, kan vara fotobioreaktorer, dvs. vattenrening med hjälp av mikroalger. Dessa system använder mikroalger och bakterier för att rena vattnet från föroreningar, kväve och fosfor.

Vattenrening med fotobioreaktorer är en relativt ny teknik. Flera aspekter gällande biologin i dessa system har ännu inte studerats i detalj. Den här avhandlingen presenterar en översikt av de alger och bakterier som är aktiva i fotobioreaktorer. Andra viktiga aspekter som tillväxt, arter samt vattenreningsförmåga har också studerats.

Ett antal försök genomfördes där alger från Mälaren tillsattes i vatten från Västerås kommunala vattenreningsanläggning. Storleken på försöken varierade mellan 250 ml och 20 liter. Det visade sig att algerna hade en bra tillväxt samt att mängden ammonium och fosfor minskade i vattnet under försöksperioden.

De alger som tillväxte mest i studien tillhörde Scenedesmus, Desmodesmus och Chlorella. Förutom alger tillväxte även ett stort antal bakterier från grupperna Proteobacteria and Bacteroidetes. Dessa bakterier visade sig syntetisera viktiga vitaminer, t.ex. vitamin B12, som algerna normalt inte kan syntetisera själva.

Sammanfattningsvis, så presenterar denna avhandling viktig information gällande alger och bakterier i en fotobioreaktor. Informationen kan vara ett viktigt bidrag till framtida utveckling av storskaliga fotobioreaktorer för vattenrening.

Place, publisher, year, edition, pages
Västerås: Mälardalen University, 2016
Series
Mälardalen University Press Dissertations, ISSN 1651-4238 ; 196
Keyword
photobioreactors, wastewater treatment, microalgae, microbiology
National Category
Water Treatment
Research subject
Energy- and Environmental Engineering
Identifiers
urn:nbn:se:mdh:diva-30045 (URN)978-91-7485-251-6 (ISBN)
Public defence
2016-01-29, Paros, Mälardalens högskola, Västerås, 09:15 (English)
Opponent
Supervisors
Funder
Knowledge Foundation, 2011006VINNOVA, 2012-01243
Available from: 2015-12-21 Created: 2015-12-21 Last updated: 2016-01-13Bibliographically approved

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